Safe load of a discontinuous angle strut (tension/compression member) An angle discontinuous strut has cross-sectional area 30 cm² and allowable working stress 625 kg/cm² based on its slenderness ratio. What is its safe load carrying capacity?

Introduction / Context:
Safe load for a member under working-stress design equals the allowable stress times the net cross-sectional area. For a strut (compression member), the allowable stress already accounts for slenderness effects.

Given Data / Assumptions:

• Area A = 30 cm².
• Allowable stress σ_allow = 625 kg/cm².
• Safe load P_safe = A * σ_allow.

Concept / Approach:
Use direct stress formula to compute the safe axial load. Unit consistency is maintained in kg and cm²; convert to tonnes at the end (1 tonne = 1000 kg).

Step-by-Step Solution:
P_safe = A * σ_allowP_safe = 30 cm² * 625 kg/cm² = 18750 kgConvert to tonnes: 18750 kg / 1000 = 18.75 tonnesClosest standard rounded safe value in options → 18 tonnes (conservative rounding).

Verification / Alternative check:
Rounding to the next lower tabulated option is conservative; detailed design would retain 18.75 t if permitted.

Why Other Options Are Wrong:

• 10, 12, 15 tonnes: underestimate capacity considerably.
• 20 tonnes: slightly higher than the computed 18.75 t (non-conservative rounding up).

Common Pitfalls:
Forgetting unit conversion or using gross instead of effective area if holes are present; here area is given as already effective.

Final Answer:
18 tonnes